The construction industry commonly uses single ply membranes to provide a waterproof barrier on flat or low-slope roofs. It is prohibitively expensive and difficult to produce and transport a single membrane that is sized to cover an entire roof surface, thus, a plurality of individual membranes are often provided and oriented in an overlapping arrangement. The overlapping portions, or splices, of these individual membranes must be secured together to ensure that the plurality of membranes form a single waterproof surface.
In many cases, flashings are used to seal certain locations of the roofing membranes where the membranes meet, such as corners or walls. One type of flashing used is referred to as a tape flashing, which is a laminate and includes a polymeric layer of thermosetting flashing material (i.e., EPDM) laminated to a layer of vulcanized tape adhesive. The polymeric layer may be provided in an uncured state and then cured by exposure to heat over time after being installed on the roof. The polymeric layer of the flashing laminates are formable when in the uncured state, which facilitates installation of the flashing laminate by allowing it to conform to the underlying surfaces (e.g. corners). However, these uncured flashing laminates are susceptible to punctures, slits, cuts and impact damage, as well as damage caused by building movement and/or wall movement prior to curing of the polymeric layer.
Flashing laminates are often provided in specific sizes and shapes designed for installation at specific locations of the roofing system or edges of the membrane. For example, flashing laminates may include those intended for installation at an outer corner of vertical walls, at the base of curb surfaces, around penetrations through the roofing system, and at a metal flashing, such as a gravel stop, provided at the edge of the roof surface. Certain areas of these flashing laminates are particularly vulnerable to damage while the flashing is in an uncured state. Specifically, the areas where the flashing laminate transitions from a horizontal surface to a vertical surface are particularly vulnerable. In addition, areas at the outer corners of vertical surfaces can also be vulnerable to damage during installation of the flashing tape.
U.S. Pat. No. 5,204,148 discloses an improved laminate cover or patch for sealing an opening in a roofing membrane. The laminate cover includes a top sheet, a lower sheet, and a layer of flowable sealing material. The top sheet includes a weather resistant material, and a complimentary shaped and sized lower sheet of a lightly cured butyl rubber having opposed tacky surfaces. The layer of a flowable sealing material, such as an uncured butyl rubber sealing compound, having a smaller dimension than that of the lower sheet, is trapped between the bottom sheet and a bottom release coated carrier. The layer of flowable sealing material is designed to provide an improved seal over an opening in a roofing membrane, and would not be effective in provided added tensile strength or puncture resistance to the laminate because the sealing material is uncured.
Thus, there is a need for an improved flashing laminate that reduces the risk of damage to the flashing during installation and during the curing period without appreciably affecting the formability of the flashing laminate.